Precision structured glass articles, integrated circuit packages, optical devices, microfluidic devices, and methods for making the same

ABSTRACT

The present disclosure relates to a reconstituted wafer- and/or panel-level package comprising a glass substrate having a plurality of cavities. Each cavity is configured to hold a single IC chip. The reconstituted wafer- and/or panel-level package can be used in a fan-out wafer or panel level packaging process. The glass substrate can include at least two layers having different photosensitivities with one layer being sufficiently photosensitive to be capable of being photomachined to form the cavities.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/633,368 filed on Jan. 23, 2020, which claims the benefit of priorityunder 35 U.S.C. 371 of International Application No. PCT/US2018/043460,filed on Jul. 24, 2018, which claims the benefit of priority under 35U.S.C. 119 of U.S. Provisional Application Nos. 62/536,103, filed Jul.24, 2017, and 62/582,297, filed Nov. 6, 2017, the content of each ofwhich is incorporated herein by reference in its entirety.

BACKGROUND Field

This disclosure relates to precision structured glass articles andmethods for making the same. In addition, this disclosure relates tointegrated circuit (“IC”) packages (e.g., wafer- and/or panel-levelpackages), optical devices, and microfluidic devices comprisingprecision structured glass articles.

Technical Background

Structured glass articles can have cavities or channels that can beuseful for a variety of applications including, for example, integratedcircuit packages, optical encapsulation, and microfluidic devices. Suchstructured glass articles can be manufactured by a variety of processesincluding, for example, photostructuring, molding, and wet etching.However, such processes can result in cavities or channels of thestructured glass article having dimensions (e.g., width, length, and/ordepth) that are not precisely controlled. Additionally, oralternatively, such processes can result in cavities or channels of thestructured glass article having a floor and/or sidewalls that are not ofoptical quality (e.g., roughened or irregular surfaces).

SUMMARY

Disclosed herein are precision structured glass articles and methods formaking the same. Such structured glass articles can be used forintegrated circuit packages, optical devices, and micro fluidic devices.

Disclosed herein is a structured glass article comprising a glasssubstrate comprising a glass cladding layer fused to a glass core layerand one or more cavities formed in the glass substrate. The glasscladding layer has a higher etch rate in an etchant than the glass corelayer.

Disclosed herein is a method for forming a structured glass article, themethod comprising applying a mask to a surface of a glass substratecomprising a glass cladding layer fused to a glass core layer such thatthe mask is disposed on the glass cladding layer. The mask comprises oneor more open regions at which the glass substrate remains uncovered bythe mask. The glass cladding layer has a higher etch rate in an etchantthan the glass core layer. The masked glass substrate is exposed to theetchant, thereby selectively etching a portion of the glass claddinglayer and forming one or more cavities in the glass substrate. The maskcan be removed from the glass substrate subsequent to the exposing.

A number of embodiments of a reconstituted wafer- and/or panel-levelpackage are described. The package includes a glass substrate having aplurality of cavities with an IC chip positioned in each cavity. Thecavities are precisely dimensioned to hold the ICs and prevent them fromshifting during processing. Also, the glass substrate can be used inplace of the conventional carrier substrate and the resin moldingcompound to eliminate or at least significantly reduce the CTEmismatches caused by those materials.

The reconstituted wafer- and/or panel-level package can be any sizeincluding traditional WLP sizes. The dimensional stability provided bythe glass substrate is especially suited for making packages usinglarger substrates such as those involved in panel-level packaging (PLP).Either way, it should be appreciated that reconstituted wafer- and/orpanel-level packages include WLPs, PLPs, and any other size of wafer-and/or panel-level packaging.

The glass substrate can have a variety of different configurations. Insome embodiments, the glass substrate includes two or more layers ofglass fused together. For example, the glass substrate can include aglass cladding layer fused to a glass base layer. In other examples, theglass substrate can include a glass base layer positioned between twoglass cladding layers.

The different layers of the glass substrate can have differentphotosensitivities. For example, the photosensitivity of the glasscladding layer or layers can be greater than that of the glass baselayer. This makes it possible to photomachine the glass cladding layerto form the cavities. In some embodiments, the glass base layer has aphotosensitivity of zero.

The differential photosensitivity between the glass cladding layer andthe glass base layer makes it possible to form cavities in the glasssubstrate that precisely fit the IC chips. In those embodiments wherethe photosensitivity of the glass base layer is zero or so low as to beinsignificant, only the glass cladding layer is removed byphotomachining and the glass base layer forms the bottom of thecavities. The glass cladding layer can have the same thickness as the ICchips so that when the chips are in the cavities, they are flush withthe top surface of the glass substrate.

Any suitable process can be used to form the cavities in the glasssubstrate. As mentioned above, one suitable process is photomachining.This can include exposing the glass cladding layer to radiation, such asultraviolet light, causing it to form crystallized regions that can beremoved via etching to form the cavities. A photomask can be used topattern the cavities on the surface of the glass substrate.

The plurality of cavities can have any suitable size. In general, thecavities are all the same size and form a regular repeating pattern onthe surface of the glass substrate that maximizes the number of packagesthat can be made per reconstituted substrate. The cavities can have anysuitable depth. As mentioned above, the cavities can be the same depthas the IC chips. In some embodiments, the depth of the cavities variesfrom approximately 50 microns to approximately 400 microns or fromapproximately 75 microns to approximately 300 microns. In someembodiments, the thickness of the glass cladding layer corresponds tothe depth of the cavities. In some embodiments, the dimensions of thecavities (width (x), length (y), and depth (z)) vary no more than 20microns from the specified value and/or from the size of the IC chip.

The reconstituted wafer- and/or panel-level package can also include anyof the other layers, coatings, and the like that are typical of suchpackages. Examples of these include an RDL, BGA, one or more protectivecoatings or encasements, and the like.

The reconstituted wafer- and/or panel-level package can be made usingany of a variety of methods. One example of a suitable method includesforming a multilayer glass substrate comprising a plurality of cavitiesand positioning IC chips in the cavities. The cavities can be formed byexposing the multilayer glass substrate to radiation through a mask toform crystallized regions that are removed by chemical etching. Aredistribution layer (“RDL”), ball grid array (“BGA”), protective layer,or the like can then be deposited on the reconstituted substrate to formthe final package.

One or more representative embodiments is provided to illustrate thevarious features, characteristics, and advantages of the disclosedsubject matter. It should be appreciated that the features,characteristics, advantages, etc., of one embodiment can be used aloneor in various combinations and sub-combinations with one another.

The Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. The Summary and the Background are not intended to identifykey concepts or essential aspects of the disclosed subject matter, norshould they be used to constrict or limit the scope of the claims. Forexample, the scope of the claims should not be limited based on whetherthe recited subject matter includes any or all aspects noted in theSummary and/or addresses any of the issues noted in the Background.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understanding the natureand character of the claimed subject matter. The accompanying drawingsare included to provide a further understanding and are incorporated inand constitute a part of this specification. The drawings illustrate oneor more embodiment(s), and together with the description, serve toexplain principles and operation of the various embodiments.

DRAWINGS

Various embodiments are disclosed in association with the accompanyingdrawings in which:

FIG. 1 is a cross-sectional schematic view of some embodiments of aglass substrate that can be used to make a precision structured glassarticle.

FIG. 2 is a cross-sectional schematic view of the glass substrate ofFIG. 1 being selectively exposed to radiation through a mask to formcrystallized regions in a cladding layer.

FIG. 3 is a cross-sectional schematic view of the glass substrate ofFIG. 2 being exposed to an optional heat treatment to further developthe crystallized regions.

FIG. 4 is a perspective view of the glass substrate of FIG. 3 afterexposure to the radiation and heat treatment to form the crystallizedregions.

FIGS. 5-6 are a cross-sectional schematic view and a perspective view,respectively, of the glass substrate of FIG. 4 after the crystallizedregions have been removed to form cavities or the glass substrate ofFIG. 7 after forming cavities therein and removing the mask.

FIG. 7 is a cross-sectional schematic view of the glass substrate ofFIG. 1 being selectively exposed to an etchant through a mask to formcavities in a cladding layer.

FIGS. 8-9 are a cross-sectional schematic view and a perspective view,respectively, of some embodiments of a reconstituted wafer- and/orpanel-level package.

FIG. 10 is a cross-sectional schematic view of the reconstituted wafer-and/or panel-level package of FIGS. 8-9 with a redistribution layerpositioned on the glass substrate and the IC chips.

FIG. 11 is a cross-sectional schematic view of the reconstituted wafer-and/or panel-level package of FIG. 10 with a ball grid array positionedon the redistribution layer.

FIG. 12 is a cross-sectional schematic view of separate IC packagesafter the reconstituted wafer- and/or panel-level package of FIG. 11 hasbeen singulated or singularized.

FIG. 13 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package in which the glasssubstrate includes cavities formed in opposing glass cladding layers.

FIG. 14 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package.

FIG. 15 is a cross-sectional schematic view of the reconstituted wafer-and/or panel-level package of FIG. 14 with a planarizing layerpositioned on the glass substrate and the IC chips.

FIG. 16 is a cross-sectional schematic view of the reconstituted wafer-and/or panel-level package of FIG. 15 with a redistribution layerpositioned on the planarizing layer and the IC chips and a ball gridarray positioned on the redistribution layer.

FIG. 17 is a plot showing the etch rate of the clad glass of anexemplary glass substrate on the x-axis and the ratio of the etch rateof the clad glass to the etch rate of the core glass of the exemplaryglass substrate on the y-axis.

FIG. 18 is a plot showing etch time on the x-axis and the removal depthon the y-axis for exemplary glass substrates with relatively thin glasscladding layers.

FIG. 19 is a plot showing the etch time on the x-axis and the removaldepth on the y-axis for exemplary glass substrates with relatively thickglass cladding layers.

FIG. 20 is a cross-sectional schematic view of some embodiments of acavity formed in a glass substrate.

FIG. 21 is a photograph of a cavity formed using a conventional wetetching process on a single-layer substrate.

FIG. 22 is a series of photographs of cavities formed using someembodiments of an etching process on a glass substrate with a glass coreand glass cladding layers.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments which areillustrated in the accompanying drawings. Whenever possible, the samereference numerals will be used throughout the drawings to refer to thesame or like parts. The components in the drawings are not necessarilyto scale, emphasis instead being placed upon illustrating the principlesof the exemplary embodiments.

Numerical values, including endpoints of ranges, can be expressed hereinas approximations preceded by the term “about,” “approximately,” or thelike. In such cases, other embodiments include the particular numericalvalues. Regardless of whether a numerical value is expressed as anapproximation, two embodiments are included in this disclosure: oneexpressed as an approximation, and another not expressed as anapproximation. It will be further understood that an endpoint of eachrange is significant both in relation to another endpoint, andindependently of another endpoint.

In various embodiments, a structured glass article includes a glasssubstrate and one or more cavities formed in the glass substrate. Insome embodiments, the glass substrate comprises a glass cladding layerfused to a glass base layer. In some of such embodiments, the one ormore cavities is formed in the glass cladding layer. For example, insome embodiments, the glass cladding layer has a higher dissolution rateor etch rate in an etchant than the glass core layer. Such adifferential dissolution rate or etch rate between the glass claddinglayer and the glass core layer can enable formation of the one or morecavities in the glass substrate using a wet etching process as describedherein. In some embodiments, the glass core layer defines a floor of theone or more cavities. Additionally, or alternatively, the glass claddinglayer defines sidewalls of the one or more cavities. In someembodiments, the floor of the one or more cavities is of opticalquality. Additionally, or alternatively, the floor of the one or morecavities is substantially flat. Additionally, or alternatively, thesidewalls of the one or more cavities are substantially straight.

In various embodiments, a method for forming a structured glass articlecomprises applying a mask to a surface of a glass substrate. In someembodiments, the glass substrate comprises a glass cladding layer fusedto a glass base layer. In some of such embodiments, the applying themask comprises applying the mask to a surface of the glass claddinglayer. The mask can be formed from a material that is resistant to anetchant. In some embodiments, the glass substrate is exposed to theetchant. For example, the exposing the glass substrate to the etchantcomprises contacting the masked glass cladding layer with the etchant toselectively etch a portion of the glass cladding layer, thereby formingone or more cavities in the glass substrate. The one or more cavitiescan have a pattern that corresponds to a pattern of an open region ofthe mask. In some embodiments, the glass cladding layer has a higherdissolution rate or etch rate in the etchant than the glass core layer.Such a differential dissolution rate or etch rate between the glasscladding layer and the glass core layer can enable formation of the oneor more cavities in the glass substrate without substantially etchingthe core layer. Thus, the core layer can act as an etch stop, which canenable the one or more cavities to have precise dimensions, opticalquality floors, substantially flat floors, and/or substantially straightsidewalls as described herein.

In some embodiments, an integrated circuit package comprises astructured glass article as described herein. For example, theintegrated circuit package comprises an integrated circuit chippositioned in each of the one or more cavities of the shaped article.Such an integrated circuit package can benefit from the precisedimensions and/or substantially straight sidewalls of the cavities asdescribed herein. For example, such dimensions and/or sidewalls canenable precise placement of the integrated circuits within the cavitiesof the package, potentially enabling a polymer filler (e.g., resinmolding compound) within the cavity to be omitted.

Integrated circuit (IC) packaging is the back-end process ofsemiconductor device fabrication, in which the block of semiconductingmaterial is packaged in a supporting case that provides an electricalconnection from the chip density to the printed circuit board densityand prevents physical damage and corrosion to the semiconductingmaterial. The case, known as a “package,” supports the electricalcontacts which connect the device to a circuit board. This process isoften referred to as packaging, but can also be referred to assemiconductor device assembly, encapsulation, or sealing.

Wafer-level packaging or wafer-level chip-scale packaging (WLP) is thetechnology of packaging an IC (e.g., chips or dies) while still part ofthe wafer, in contrast to the more conventional method of slicing thewafer into individual circuits (dice) and then packaging them. WLP canenable integration of wafer fabrication, packaging, test, and burn-in atthe wafer-level in order to streamline the manufacturing processundergone by a device from silicon start to customer shipment. WLP caninclude extending the wafer fabrication processes to include deviceinterconnection and device protection processes. Most other kinds ofpackaging do wafer dicing first, and then put the individual die in aplastic package and attach the solder bumps. WLP involves attaching thetop and bottom outer layers of packaging and the solder bumps to ICswhile still in the wafer and then dicing the wafer.

One type of WLP is fan-in (FI), which has all the contact terminalswithin the footprint of the die. Such a configuration can pose asignificant limitation when adjusting the layout of the contactterminals to match the design of the next-level substrate. Fan-out (FO)is another type of WLP that represents a compromise between die-levelpackaging and FI WLP. FO WLP involves dicing the semiconductor wafer andthen embedding the singularized ICs in a reconstituted or artificialmolded wafer. The dies are separated from each other on thereconstituted wafer by a distance that is big enough to allow thedesired FO redistribution layer (RDL) to be manufactured using standardWLP processes. The FO WLP provides a way to connect the smaller die withfine lead pitch to the larger lead pitch of a printed circuit board.

Although FO WLP has many advantages such as low cost, package sizereduction, and fine lead pitch, conventional FO WLP presents a number ofchallenges. For example, two of the most significant challenges are dieshift and warpage. Die shift can be caused by the process used to embedthe die on the reconstituted wafer. The conventional FO WLP processincludes coating a carrier substrate with adhesive, placing the siliconchips on the adhesive, applying the resin molding compound to fill thespaces between the chips, removing the carrier substrate, flipping thereconstituted substrate over, and forming the RDL and/or ball grid arrayon the exposed chips embedded in the resin molding compound. Die shiftcan be caused by the flow of the molding compound between the diesand/or the resin volume shrinkage that may occur during cross-linking.Any shift in the die's position, translationally and/or rotationallyposes challenges for subsequent processing steps and can result in badpackages.

Warpage can result from the different rates at which the variousmaterials in the reconstituted wafer expand and/or contract in responseto temperature changes. The coefficients of thermal expansion (CTE) ofthe carrier substrate, silicon die, resin molding compound, and/or theRDL on the reconstituted wafer can vary significantly. For example, theCTE of silicon is 2-3 ppm/° C. compared to the CTE of the moldingcompound, which exceeds 8 ppm/° C. The different CTEs can cause thereconstituted wafer to warp in response to temperature changes. Theproblems associated with die shift and warpage can be amplified as thesize of the reconstituted substrate increases. The challenges ofconventional WLP can be mitigated by using the structured glass articledescribed herein as the package.

In some embodiments, the integrated circuit package is configured as areconstituted wafer- and/or panel-level package that includes astructured glass substrate having a plurality of cavities, each of whichis sized to receive and hold an integrated circuit (IC) chip (e.g., asingle IC chip). The glass substrate can reduce die shift and warpagecaused by conventional FO WLP processing. For example, die shift iseliminated or at least reduced because the IC chips are physically heldin place by the cavities. Additionally, or alternatively, warpage iseliminated or reduced because the CTE of the glass substrate can be muchcloser to that of the silicon IC chips compared to polymer materials.

The reconstituted wafer- and/or panel-level package can offer one of themost compact package footprints, providing increased functionality,improved thermal performance and finer lead pitch interconnection to theprinted circuit board. The manufacturing process steps can be performedin parallel at the substrate level rather than sequentially onindividual chips to achieve a package that is the same size or slightlylarger than the die. The resultant package can have dielectrics, thinfilm metals, and solder bumps directly on the surface of the die with noadditional packaging. The basic structure of the reconstituted wafer-and/or panel-level package can have an active surface with polymercoatings and bumps with bare silicon enclosed in the cavity in the glasssubstrate.

In some embodiments, an optical device comprises a structured glassarticle as described herein. For example, the optical device isconfigured as an optical package comprising an optically active objectencapsulated within each of the one or more cavities of the shapedarticle. Such an optical package can benefit from the optically clearand/or substantially flat floor of the cavities as described herein. Forexample, such floors can enable precise optical analysis and/ormanipulation of the optically active object.

In some embodiments, a microfluidic device comprises a structured glassarticle as described herein. For example, the microfluidic device isconfigured as a flow cell, a microreactor, or another microfluidicdevice. A fluid can flow through the one or more cavities of the shapedarticle for analysis, reaction, or another fluidic function. Such amicrofluidic device can benefit from the precise dimensions,substantially flat floor, and/or substantially straight sidewalls of thecavities as described herein. For example, such dimensions, floor,and/or sidewalls can enable precise flow of the fluid within thecavities.

FIG. 1 is a cross-sectional schematic view of some embodiments of aglass substrate 100. The glass substrate 100 includes a glass base orcore layer 110 coupled to a first or upper glass cladding layer 105 anda second or lower glass cladding layer 107. The glass substrate 100includes multiple glass layers and can be considered a glass laminate.In some embodiments, the layers 105, 107, 110 are fused together withoutany adhesives, polymer layers, coating layers or the like positionedbetween them. In other embodiments, the layers 105, 107, 110 are coupled(e.g., adhered) together using adhesives or the like.

The glass substrate 100 can have any suitable composition and be madeusing any suitable process. Examples of suitable glass compositions caninclude alkaline-earth aluminoborosilicate glasses, zinc borosilicateglasses, and soda-lime glass as well as glass ceramics, such as thoseenriched with magnesium oxide, yttria, beryllia, alumina, or zirconia.In general, the glass substrate 100 and any of the layers 105, 107, 110in the glass substrate 100 can have any of the compositions disclosed inthe '451 patent or the '266 application or be made using any of theprocesses disclosed in the '451 patent or the '266 application, each ofwhich is referenced at the end of the description.

The glass substrate 100 is configured so that at least one of the glasscladding layers 105, 107 and the glass base layer 110 have differentphysical dimensions and/or physical properties that allow for selectiveremoval of the at least one glass cladding layer 105, 107 relative tothe glass base layer 110 to form precisely dimensioned cavities 425,which can be sized and shaped to receive IC chips, receive an opticallyactive object, and/or function as microfluidic channels as describedherein.

One aspect of the glass substrate 100 that can vary widely is thethickness of the layers 105, 107, 110. For example, the layers 105, 107,110 can all have the same thickness or different thicknesses or two ofthe layers can be the same thickness while the third layer has adifferent thickness. In some embodiments, it is desirable for one orboth of the glass cladding layers 105, 107 to have a thickness that isthe same or substantially the same for all practical purposes as thethickness of an IC chip being packaged (e.g., as shown in FIGS. 8-9 ).In other embodiments, it is desirable for one or both of the glasscladding layers 105, 107 to have a thickness that is smaller than thethickness of an IC chip being packaged (e.g., as shown in FIGS. 14-16 ).In some embodiments, it is desirable for one or both of the glasscladding layers 105, 107 to have a thickness that is precisely sized formicrofluidic flow.

In some embodiments, one or both of the glass cladding layers 105, 107are approximately 10 microns to approximately 400 microns thick,approximately 10 microns to approximately 50 microns thick,approximately 70 microns to approximately 400 microns thick, orapproximately 100 microns to approximately 300 microns thick. Forexample, one or both of the cladding layers 105, 107 are at leastapproximately 10 microns thick, at least approximately 20 microns thick,at least approximately 50 microns thick, at least approximately 70microns thick, or at least approximately 100 microns thick.Additionally, or alternatively, one or both of the cladding layers 105,107 are no more than 400 microns thick, no more than 300 microns thick,no more than 200 microns thick, no more than 100 microns thick, no morethan 50 microns thick, or no more than 30 microns thick. Thesethicknesses can correspond to the thickness of IC chips that commonlyundergo FO WLP processing as described herein or can be less than thethickness of such IC chips also as described herein. It should beappreciated, however, that the glass cladding layers 105, 107 can haveother thicknesses, particularly, when used with IC chips having smalleror larger thicknesses than those disclosed.

Another aspect of the glass substrate 100 that can vary widely is theglass composition of the layers 105, 107, 110. For example, the layers105, 107, 110 can all have the same glass composition or different glasscompositions or two of the layers can have the same glass compositionwhile the third layer has a different glass composition. In general, itis desirable for one or both of the glass cladding layers 105, 107 tohave a glass composition that is different than the glass composition ofthe glass base layer 110. This provides the glass cladding layers 105,107 certain properties that make them suitable to the formation of thecavities 425.

In some embodiments, the glass compositions of the layers 105, 107, 110can vary such that the photosensitivity of the layers 105, 107, 110varies. For example, it can be desirable for one or both of the glasscladding layers 105, 107 to have a photosensitivity that is differentthan the glass base layer 110. The different photosensitivities betweenthe layers 105, 107, 110 can make it possible to form the cavities 425in the surface of the glass substrate 100. For example, the glasscladding layers 105, 107 can be sufficiently photosensitive that theycan be photomachined to form the cavities 425. On the other hand, theglass base layer 110 can be sufficiently non-photosensitive that it isnot susceptible to being photomachined.

In some embodiments, it is desirable for one or both of the glasscladding layers 105, 107 to have a photosensitivity that is greater thanthe photosensitivity of the glass base layer 110. This is especially thecase for the glass cladding layer 105, 107 in which the cavities 425 areformed. The glass base layer 110 can have a photosensitivity that iszero or sufficiently close to zero that it is insusceptible to beingphotomachined to any significant extent.

In some embodiments, the glass compositions of the layers 105, 107, 110can vary such that the durability of the layers 105, 107, 110 in anetchant varies. For example, it can be desirable for one or both of theglass cladding layers 105, 107 to have a dissolution rate in the etchantthat is different than the glass base layer 110. The differentdurability between the layers 105, 107, 110 makes it possible to formthe cavities 425 in the surface of the glass substrate 100. For example,the glass cladding layers 105, 107 can have a sufficiently highdissolution rate in the etchant that they can be etched to form thecavities 425. On the other hand, the glass base layer 110 can have asufficiently low dissolution rate in the etchant that it is notsubstantially susceptible to being etched. Thus, the glass base layer110 can act as an etch stop to limit the depth to which the glasssubstrate 100 can be etched using the etchant.

In some embodiments, it is desirable for one or both of the glasscladding layers 105, 107 to have a dissolution rate in the etchant thatis greater than the dissolution rate of the glass base layer 110. Thisis especially the case for the glass cladding layer 105, 107 in whichthe cavities 425 are formed. The glass base layer 110 can have adissolution rate in the etchant that is zero or sufficiently close tozero that it is insusceptible to being etched to any significant extent.

It should be appreciated that numerous changes can be made to theembodiments of the glass substrate 100 shown in FIG. 1 . For example, insome embodiments, the glass substrate 100 can include only two glasslayers 105, 110. In other embodiments, the glass substrate 100 caninclude four or more glass layers. Numerous other variations are alsocontemplated.

In some embodiments, cavities 425 are formed in the glass substrate 100to transform the glass substrate into a structured article as describedherein. For example, the cavities 425 can be photomachined in thesurface of the glass substrate 100 using the process depicted in FIGS.2-4 . Referring to FIG. 2 , in some embodiments, the first step in theprocess is to expose the cladding layer 105 to a source of radiation 220through a photomask 215 to pattern the cavities 425. Any suitable sourceof radiation 220 can be used in the photomachining process, providedthat it is capable of altering the properties of the glass claddinglayer 105. One example of a suitable source of radiation is ultravioletlight.

The photomask 215 can be made of any suitable material and have anysuitable pattern. In general, the photomask 215 should be made ofmaterial that is capable of effectively blocking the radiation 220 fromreaching and/or affecting the surface of the glass substrate 100. Thephotomask can be positioned on the surface of the glass cladding layer105 or a distance above the surface of the glass cladding layer 105. Thepattern produced by the photomask 215 can be an array of regularlyrepeating rectangular shapes such as those shown in FIGS. 2-4 . Forexample, the shapes patterned by the photomask 215 can correspondclosely to the shape of the IC chips as described herein. Other shapescan also be used and can generally correspond closely to the shape ofthe IC chip and/or be capable of securely holding the IC chip inposition on the glass substrate 100.

In some embodiments, the glass cladding layer 105 is sufficientlyphotosensitive that the radiation 220 changes its crystallinityproperties. For example, the glass cladding layer 105 comprises or isformed from a glass composition that undergoes a change in crystallinityupon exposure to the radiation 220 alone. Additionally, oralternatively, the glass cladding layer 105 comprises or is formed froma glass composition that undergoes small scale physical changes (e.g.,nanoscale changes) that can be difficult to detect when exposed to theradiation 220 such as the formation of nucleation centers. These glasscompositions can be subjected to an additional, optional, heat treatmentto complete the change in crystallinity.

FIG. 3 shows some embodiments of the glass substrate 100 undergoing anoptional heat treatment. The glass substrate 100 can be exposed to asource of heat 330. It should be appreciated that any suitable heatsource can be used to provide the heat treatment.

In some embodiments, the radiation and optional heat treatments formcrystallized regions 325 in the glass cladding layer 105 as shown inFIGS. 3-4 . For example, a secondary crystalline phase forms in thecrystallized regions 325 that is capable of being selectively removed bya physical and/or chemical procedure such as selective etching—e.g., wetetching using acid or the like. In some embodiments, the selectiveremoval of the secondary crystalline phase is enabled by differences insolubility between the crystallized regions 325 and the portions of theglass cladding layer 105 not exposed to radiation (e.g., uncrystallizedregions) when they are exposed to an etchant medium such as hydrofluoricacid. The solubility difference can produce an etch-rate difference thatcauses the secondary crystalline phase to etch faster than the unexposedglass.

In some embodiments, the crystallized regions 325 etch at least 1.5times faster, at least 2 times faster, at least 5 times faster, at least10 times faster, at least 20 times faster, or at least 100 times fasterthan the unexposed portions (e.g., uncrystallized regions) of the glasscladding layer 105. This feature of etch-rate and/or solubilitydifferentiation may or may not be present in all photosensitive glasscompositions. Accordingly, all photomachinable glass compositions arephotosensitive glass compositions with a nonzero photosensitivity, butphotosensitive glass compositions are not necessarily photomachinable.

FIGS. 5-6 show the glass substrate 100 with the crystallized regions 325removed. The glass substrate 100 is now ready to receive the IC chips525. In some embodiments, the portion of the glass cladding layer 105not exposed to the radiation 220 (e.g., the unexposed portion or theuncrystallized portion) is not substantially affected by the processused to remove the crystallized regions 325. In other embodiments, thethickness of the unexposed areas of the glass cladding layer 105 isreduced by the removal process. Either way, the glass cladding layer 105can have any of the thicknesses described above. For example, in thoseembodiments in which the thickness of the unexposed areas is reduced,the starting thickness can be increased to offset the amount that isremoved by the etching process so that the final thickness correspondsto the desired thickness (e.g., corresponding to the thickness of the ICchips 525).

In some embodiments, cavities 425 can be formed in the surface of theglass substrate 100 using the process depicted in FIG. 7 . In someembodiments, the process comprises forming a mask 315 on a surface ofthe glass substrate 100. For example, the mask 315 is formed on thesurface of the glass cladding layer 105 and/or the glass cladding layer107. The mask 315 can be formed by printing (e.g., inkjet printing,gravure printing, screen printing, or another printing process) oranother deposition process. In some embodiments, the mask 315 isresistant to the etchant (e.g., the etchant that will be used to etchthe cavities 425 in the glass substrate 100). For example, the mask 315can comprise an acrylic ester, a multifunctional acrylaten-vinylcaprolactam, or another suitable mask material. In someembodiments, the mask 315 is formed from an ink material comprising aprimer to enhance adhesion between the mask and the glass substrate 100.Such enhanced adhesion can reduce seepage of the etchant between themask 315 and the glass substrate 100, which can help to enable theprecise cavities described herein.

In some embodiments, the mask 315 comprises one or more open regions atwhich the glass substrate 100 remains uncovered. The open regions of themask 315 can have a pattern corresponding to the desired pattern of thecavities 425 to be formed in the glass substrate 100. For example, thepattern of the mask 315 can be an array of regularly repeatingrectangular shapes (e.g., to receive IC chips as described herein). Insuch embodiments, the shapes patterned by the mask 315 can correspondclosely to the shape of the IC chips. Other shapes also can be used, andthe shapes can correspond closely to the shape of the IC chip or becapable of securely holding the IC chip in position on the glasssubstrate 100. Thus, the mask 315 can be configured as an etch mask toenable selective etching of the glass cladding layer 105 and/or theglass cladding layer 107 and form the cavities 425 in the glasssubstrate 100 as described herein.

In some embodiments, the glass substrate 100 with the mask 315 disposedthereon is exposed to the etchant 320. For example, the glass claddinglayer 105 and/or the glass cladding layer 107 is contacted with theetchant 320 as shown in FIG. 7 , thereby selectively etching an exposedportion of the respective glass cladding layer that is uncovered by themask 315 and forming the cavities 425 in the glass substrate, therebytransforming the substrate into the shaped article. Thus, following theforming the cavities 425, the glass substrate 100 can be referred to asthe shaped article.

In some embodiments, the glass substrate 100 with the mask 315 disposedthereon is exposed to the etchant 320 at an etching temperature and foran etching time. For example, the etching temperature is about 20° C.,about 22° C., about 25° C., about 30° C., about 35° C., about 40° C.,about 45° C., or about 50° C., or any ranges defined by any combinationof the stated values. A lower etching temperature can help to maintainthe integrity of the mask 315 during the etching, which can enable anincreased etching time and/or improved cavity shape as described herein.Additionally, or alternatively, the etching time can be about 10minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50minutes, about 55 minutes, about 60 minutes, about 65 minutes, about 70minutes, about 75 minutes, about 80 minutes, about 85 minutes, or about90 minutes, or any ranges defined by any combination of the statedvalues. A relatively long etching time can enable substantially straightsidewalls of the cavities 425 as described herein.

In some embodiments, the glass cladding layer 105 and/or the glasscladding layer 107 etch at least 1.5 times faster, at least 2 timesfaster, at least 5 times faster, at least 10 times faster, at least 20times faster, or at least 100 times faster than the glass core layer110. Additionally, or alternatively, a ratio of the etch rate of theglass cladding layer 105 and/or the glass cladding layer 107 to the etchrate of the glass core layer 110 is about 5, about 10, about 15, about20, about 25, about 30, about 35, about 40, about 45, about 50, about55, about 60, about 65, about 70, about 75, about 80, about 85, about90, about 95, about 100, or any ranges defined by any combination of thestated values.

In some embodiments, the forming the cavities 425 comprises etchingsubstantially entirely through the glass cladding layer 105 and/or theglass cladding layer 107 to expose a portion of the glass core layer 110at the bottom of the cavities. Thus, the sidewalls of the cavities 425are defined by the glass cladding layer 105 and/or the glass claddinglayer 107, and the floors of the cavities are defined by the glass corelayer 110. In some embodiments, the glass core layer 110 is notsubstantially etched during the forming the cavities 425. Thus, theglass core layer 110 serves as an etch stop that determines the depth ofthe cavities 425.

In some embodiments, the floor of the one or more cavities is of opticalquality. For example, a surface roughness of the floor of the cavities425 is at most about 50 nm, at most about 40 nm, at most about 30 nm, atmost about 20 nm, at most about 10 nm, at most about 9 nm, at most about8 nm, at most about 7 nm, at most about 6 nm, or at most about 5 nm.Such low surface roughness can be enabled by the etch stop provided bythe glass core layer 110 and/or agitating the etchant during the etchingto remove etching byproducts from the cavity. Additionally, oralternatively, such low surface roughness can enable light to passthrough the floor (e.g., for optical activation and/or analysis of anobject or material disposed within the cavities) without substantialdistortion.

In some embodiments, the floor of the one or more cavities issubstantially flat. For example, a difference between a first depth ofthe cavity at a first position along the perimeter of the cavity and asecond depth of the cavity at a second position along the perimeter ofthe cavity opposite the first position (e.g., diametrically opposed) isat most about 5 μm, at most about 4 μm, at most about 3 μm, at mostabout 2 μm, at most about 1 μm, at most about 0.9 μm, at most about 0.8μm, at most about 0.7 μm, at most about 0.6 μm, at most about 0.5 μm, atmost about 0.4 μm, at most about 0.3 μm, at most about 0.2 μm, or atmost about 0.1 μm. Such a low depth difference can be enabled by theetch stop provided by the glass core layer 110. For example, the depthof the cavity can be determined primarily by the thickness of the glasscladding layer 105 and/or the glass cladding layer 107 without changingsubstantially as a result of changes in etch temperature and/or etchtime.

In some embodiments, the sidewalls of the one or more cavities aresubstantially straight. For example, an angle formed between thesidewall and the floor of the cavity is at most about 30°, at most about25°, at most about 20°, at most about 19°, at most about 18°, at mostabout 17°, at most about 16°, or at most about 15°. Additionally, oralternatively, a difference between a width of the cavity at a top ofthe cavity (e.g., near the surface of the glass substrate) and a widthof the cavity at a bottom of the cavity (e.g., near the floor of thecavity) is at most about 1 mm, at most about 0.9 mm, at most about 0.8mm, at most about 0.7 mm, at most about 0.6 mm, or at most about 0.5 mm.In some of such embodiments, the depth of the cavity is at least about50 μm, at least about 60 μm, at least about 70 μm, at least about 80 μm,or at least about 90 μm. Such a low angle of the sidewalls can beenabled by an increased etching time, which can be enabled by the etchstop provided by the glass core layer 110. For example, the etching timecan be extended to remove material at the intersection between thesidewalls and the floor near the bottom of the cavity withoutsubstantially increasing the depth of the cavity. Removing such materialcan result in a straighter sidewall compared to conventional wet etchingprocesses.

In some embodiments, following the forming the cavities, the mask 315 isremoved from the glass substrate 100. For example, the removing the mask315 comprises contacting the mask with a solvent, thereby removing themask from the surface of the glass substrate. In some embodiments, thesolvent is water. For example, the removing the mask 315 comprisessubmerging the glass substrate 100 with the mask 315 disposed thereoninto water, thereby removing the mask from the surface of the glasssubstrate. FIGS. 5-6 are cross-sectional schematic and perspectiveviews, respectively, of the glass substrate 100 with the cavities 425formed therein and the mask 315 removed therefrom.

One advantage of the cavities 425 is that they can be formed withprecision that is generally unattainable using conventional processingtechniques. The depth of the cavities 425 is especially precise in thoseembodiments in which the base layer 110 is unaffected by the etchingprocess. In such embodiments, the glass cladding layer 105 can be etchedaway until the etchant reaches the glass base layer 110 and/or the glassbase layer 110 is exposed at the bottom of the cavities 425. Thus, thesides of the cavities 425 are defined by the glass cladding layer 105and/or the glass cladding layer 107, and the floor or bottom is definedby the base layer 110. This gives the cavities 425 a precise depth.

The cavities 425 shown in FIGS. 5-6 have a rectangular shape thatcorresponds to the IC chips 525. It should be appreciated, however, thatthe cavities 425 can have any suitable shape. For example, the cavities425 can have a square shape, a circular shape, or any other polygonal ornon-polygonal shape.

In some embodiments, the shaped article can be used as an integratedcircuit package. For example, the IC chips 525, which can be diced froman underlying wafer, are placed in the cavities 425 to form areconstituted wafer- and/or panel-level package 200, as shown in FIGS.8-9 . The cavities 425 can be configured to receive any suitable ICchips 525. In some embodiments, the IC chips 525 are silicon based ICchips.

In some embodiments, the cavities 425 are each substantially the samesize (width (x), length (y), and/or depth (z)) as the IC chips 525 toallow an exact fit of an IC chip 525 in each corresponding cavity 425.As mentioned above, it can be desirable for the IC chips 525 to be flushwith the top surface of the glass cladding layer 105 and/or the glasscladding layer 107. Nevertheless, there may be situations where the topof the IC chips 525 may not be perfectly flush with the glass claddinglayer 105 and/or the glass cladding layer 107. This may be acceptableprovided the resulting reconstituted substrate is capable of beingfurther processed to produce the final package.

The IC chips 525 can generally vary 1-2 microns in size. In someembodiments, the width (x), length (y), and/or depth (z) of each cavity425 varies by no more than 20 microns, no more than 10 microns, no morethan 5 microns, or no more than 4 microns relative to: (a) a target sizeof the dimension(s) of the cavities 425, (b) the actual size of thecorresponding dimension(s) of the IC chip 525, and/or (c) the targetsize of the corresponding dimension(s) of the IC chips 525. For example,the width (x), length (y), and/or depth (z) of each cavity 425 can be nomore than 20 microns larger, no more than 10 microns larger, no morethan 5 microns larger, or no more than 4 microns larger than: (a) atarget size of the dimension(s) of the cavities 425, (b) the actual sizeof the corresponding dimension(s) of the IC chip 525, and/or (c) thetarget size of the corresponding dimension(s) of the IC chips 525. Thelaminate structure of the glass substrate 100 can provide particularlyprecise control of the depth of the cavities 425 compared toconventional substrates.

FIG. 10 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package 200 with an RDL 640positioned on the surface thereof. In some embodiments, the RDL 640covers the surface of the glass substrate 100 including the claddinglayer 105 and the chips 525. The RDL 640 can include a single physicallayer or multiple separate layers that combine to form the RDL 640. Inthe embodiments shown in FIG. 10 , the RDL 640 includes leads 630 and635 that pass from the IC chips 525 to the upper surface of the RDL 640.The leads 630 can be within the dimensions of the IC chips 525, and theleads 635 can extend outside the dimensions of the IC chips 525.

FIG. 11 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package 200 with a BGApositioned on the RDL 640. In some embodiments, the BGA includes solderbumps 730 and 735 formed on the leads 630, 635, respectively. In someembodiments, the reconstituted wafer- and/or panel-level package 200 issingulated or singularized to produce separate packaged units 300 asshown in FIG. 12 . For example, each packaged unit 300 includes one ofthe IC chips 525. Separation may be performed by dicing (e.g.,mechanical and/or laser dicing) or any other suitable separationtechnique.

FIG. 13 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package 400 having cavities inboth of the glass cladding layers 105, 107. The cavities in the glasscladding layer 107 can be formed using the same or similar process usedto form the cavities in the glass cladding layer 105. In someembodiments, the base layer 110 may be non-transmissive to the radiation(e.g., UV light) so that exposing one of the glass cladding layers 105,107 to radiation has substantially no effect on the other glass claddinglayer 105, 107. The cavities 425 can be formed in the glass claddinglayer 105 and the glass cladding layer 107 simultaneously or separately.For example, masks 315 can be formed on both glass cladding layers 105,107, and the cavities can be formed in both glass cladding layerssimultaneously by submerging the glass substrate 100 in the etchant.

The cavities can have a variety of configurations. In some embodiments,the cavities are all the same size and/or form the same pattern on thesurface of the glass substrate 100. In other embodiments, the cavitiesin one glass cladding layer 105, 107 are different sizes or shapes thanthe cavities in the other glass cladding layer 105, 107. In otherembodiments, the pattern of the cavities on the glass cladding layers105, 107 may be different.

As shown in FIG. 13 , ICs 625 can be placed in the cavities in the glasscladding layer 107 to form dual-sided packaged integrated circuits. Itshould be appreciated that other embodiments are also possible. Forexample, the cavities in one glass cladding layer 105, 107 may be leftempty while the cavities in the other glass cladding layer 105, 107 arefilled with ICs.

FIG. 14 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package 200. The reconstitutedwafer- and/or panel-level package 200 shown in FIG. 14 is similar to thereconstituted wafer- and/or panel-level package 200 shown in FIG. 8 ,except that one or both of the glass cladding layers 105, 107 has athickness that is smaller than the thickness of the IC chip 525 beingpackaged. For example, a portion of the IC chip 525 disposed within thecavity 425 protrudes beyond the surface of the glass cladding layer 105as shown in FIG. 14 . The cavities 425 can be formed using any processas described herein (e.g., photomachining and/or etching).

In some embodiments, a thickness of one or both of the glass claddinglayers 105, 107 and/or a depth of the cavity 425 is about 5% of athickness of the IC chip, about 10% of a thickness of the IC chip, about20% of a thickness of the IC chip, about 30% of a thickness of the ICchip, about 40% of a thickness of the IC chip, about 50% of a thicknessof the IC chip, about 60% of a thickness of the IC chip, about 70% of athickness of the IC chip, about 80% of a thickness of the IC chip, about90% of a thickness of the IC chip, or any ranges defined by anycombination of the stated values. For example, in some embodiments inwhich the IC chip 525 has a thickness of about 100 μm to about 200 μm, athickness of one or both of the glass cladding layers 105, 107 and/or adepth of the cavity 425 can be about 20 μm. Such relatively shallowcavities can help to maintain the IC chip in place during processing(e.g., avoid die shifting or warping) as described herein and/or enabledie-lifting (e.g., to remove and/or reposition the IC chip).

FIG. 15 is a cross-sectional schematic view of the reconstituted wafer-and/or panel-level package 200 shown in FIG. 14 with a planarizing layer540 positioned on the glass substrate 100 and/or the IC chips 525. Forexample, the planarizing layer 540 can be positioned on the glasssubstrate to fill interstitial spaces between adjacent IC chips 525.Additionally, or alternatively, the planarizing layer 540 can besubstantially coplanar with upper surfaces of the IC chips 525 such thatthe planarizing layer and the IC chips cooperatively define asubstantially flat surface for deposition of a redistribution layerand/or ball grid array as described herein. In some embodiments, theplanarizing layer 540 comprises or is formed from a polymeric material(e.g., a resin or epoxy molding compound). For example, the planarizinglayer comprises or is formed from a resin or epoxy molding compound usedas the packaging material in a conventional FO WLP process.

FIG. 16 is a cross-sectional schematic view of the reconstituted wafer-and/or panel-level package 200 shown in FIG. 15 with a redistributionlayer 640 positioned on the planarizing layer 540 and/or the IC chipsand a ball grid array 730, 735 positioned on the redistribution layer.The redistribution layer 640 (including leads 630, 635) and/or ball gridarray (including solder bumps 730, 735) can be configured as describedherein in reference to FIGS. 10-12 .

FIG. 17 is a cross-sectional schematic view of some embodiments of areconstituted wafer- and/or panel-level package 200 with an RDL 640positioned on the surface thereof. FIG. 10 is a cross-sectionalschematic view of some embodiments of a reconstituted wafer- and/orpanel-level package 200 with an RDL 640 positioned on the surfacethereof.

In various embodiments, a reconstituted wafer- and/or panel-levelpackage is described as comprising a glass substrate comprising aplurality of cavities and an IC positioned in each one of the pluralityof cavities in the glass substrate. It should be noted that such areconstituted wafer- and/or panel-level package may have additionalcavities with or without ICs positioned therein. For example, in someembodiments, a reconstituted wafer- and/or panel-level package comprisesa plurality of cavities with an IC positioned in each one of theplurality of cavities and one or more additional cavities that are freeof an IC positioned therein. In other embodiments, a reconstitutedwafer- and/or panel-level package comprises a plurality of cavities withan IC positioned in each one of the plurality of cavities and is free ofadditional cavities.

In some embodiments, a reconstituted wafer- or panel-level packagecomprises a glass substrate comprising a glass cladding layer fused to aglass base layer, the glass substrate comprising a plurality ofcavities, and an integrated circuit chip positioned in each one of theplurality of cavities in the glass substrate. The glass cladding layercan be more susceptible to dissolution than the glass base layer. Thephotosensitivity of the glass cladding layer can be greater than thephotosensitivity of the glass base layer. The photosensitivity of theglass base layer can be substantially zero. The glass cladding layer canbe photomachinable. The glass base layer can form the bottom of theplurality of cavities in the glass substrate. The glass cladding layercan form the sides of the plurality of cavities in the glass substrate.Each of the plurality of cavities can be at least approximately 50microns deep. Each of the plurality of cavities can be no more than 400microns deep. Each of the plurality of cavities can be approximately 50microns to approximately 400 microns deep. A width, a length, and/or adepth of the cavity can be within 20 microns of a width, a length,and/or a depth, respectively, of the integrated circuit chip positionedin the cavity. A width, a length, and/or a depth of the cavity can bewithin 5 microns of a width, a length, and/or a depth, respectively, ofthe integrated circuit chip positioned in the cavity. The glass claddinglayer can be approximately 50 microns to 400 microns thick. Thereconstituted wafer- and/or panel-level package can comprise aredistribution layer and/or a ball grid array. The reconstituted wafer-and/or panel-level package can comprise a wafer level package and/or apanel level package.

In some embodiments, a reconstituted wafer- and/or panel-level packagecomprises a glass substrate comprising a glass cladding layer fused to aglass base layer, the glass substrate comprising a plurality ofcavities, and an integrated circuit chip positioned in each one of theplurality of cavities in the glass substrate, wherein the glass claddinglayer forms the sides of each of the plurality of cavities and the glassbase layer forms the bottom of each of the plurality of cavities, andwherein the glass cladding layer is photomachinable and the glass baselayer has a photosensitivity of substantially zero. Each of theplurality of cavities can be approximately 20 microns to approximately400 microns deep. The glass cladding layer can be approximately 20microns to approximately 400 microns thick. The reconstituted wafer-and/or panel-level package comprise a redistribution layer and/or a ballgrid array.

In some embodiments, a method for making a reconstituted wafer- and/orpanel-level package comprises forming a glass substrate comprising aglass cladding layer fused to a glass base layer, the glass substratecomprising a plurality of cavities, wherein the photosensitivity of theglass cladding layer is greater than the photosensitivity of the glassbase layer, and positioning an integrated circuit chip in each of theplurality of cavities in the glass substrate. The method can compriseforming the plurality of cavities in the glass substrate. Forming theplurality of cavities in the glass substrate can comprise exposing theglass cladding layer to ultraviolet radiation to form a crystallizedregion and removing the crystallized region from the glass claddinglayer. Forming the plurality of cavities in the glass substrate cancomprise exposing the glass cladding layer to ultraviolet radiation toform exposed regions and unexposed regions, wherein the exposed regionshave a higher dissolution rate than the unexposed regions. The methodcan comprise photomachining the glass substrate to form the plurality ofcavities in the glass substrate. The method can comprise forming aredistribution layer on each integrated circuit chip. The method cancomprise forming a ball grid array on the redistribution layer.

In some embodiments, a packaged integrated circuit, comprises a glasssubstrate comprising a glass cladding layer fused to a glass base layer,the glass substrate comprising a cavity, and an integrated circuit chippositioned in the cavity in the glass substrate. The glass claddinglayer can be more susceptible to dissolution than the glass base layer.The photosensitivity of the glass cladding layer can be greater than thephotosensitivity of the glass base layer. The photosensitivity of theglass base layer can be substantially zero. The glass cladding layer canbe photomachinable. The glass base layer can form the bottom of thecavity in the glass substrate. The glass cladding layer can form thesides of the cavity in the glass substrate. The packaged integratedcircuit can comprise a redistribution layer positioned over theintegrated circuit and the glass substrate. The packaged integratedcircuit can comprise a ball grid array positioned over theredistribution layer. A width, a length, and/or a depth of the cavitycan be within 20 microns of a width, a length, and/or a depth,respectively, of the integrated circuit chip positioned in the cavity. Awidth, a length, and/or a depth of the cavity can be within 5 microns ofa width, a length, and/or a depth, respectively, of the integratedcircuit chip positioned in the cavity.

In some embodiments, a structured glass article comprises a glasssubstrate comprising a glass cladding layer fused to a glass core layerand one or more cavities formed in the glass substrate, wherein theglass cladding layer has a higher etch rate in an etchant than the glasscore layer. The one or more cavities can be formed in the glass claddinglayer. The glass core layer can define a floor of the one or morecavities. A floor of the one or more cavities can be of optical quality.A floor of the one or more cavities can comprise a surface roughness ofat most about 20 nm. A difference between a first depth of one of theone or more cavities at a first position along the perimeter of thecavity and a second depth of the one of the one or more cavities at asecond position along the perimeter of the cavity opposite the firstposition can be at most about 5 μm. The glass cladding layer can definesidewalls of the one or more cavities. Sidewalls of the one or morecavities can be substantially straight. An angle formed between asidewall and a floor of the one or more cavities can be at most about30°. A difference between a first width of one of the one or morecavities at a top of the cavity and a second width of the one of the oneor more cavities at a bottom of the cavity can be at most about 1 mm. Adepth of the one of the one or more cavities can be at least about 50μm. In some embodiments, an integrated circuit package comprises thestructured glass article and an integrated circuit chip disposed withinthe one or more cavities. In some embodiments, an optical devicecomprises the structured glass article. In some embodiments, amicrofluidic device comprises the structured glass article.

In some embodiments, a method for forming a structured glass articlecomprises applying a mask to a surface of a glass substrate comprising aglass cladding layer fused to a glass core layer such that the mask isdisposed on the glass cladding layer, the mask comprising one or moreopen regions at which the glass substrate remains uncovered by the mask,the glass cladding layer having a higher etch rate in an etchant thanthe glass core layer, and exposing the masked glass substrate to theetchant, thereby selectively etching a portion of the glass claddinglayer and forming one or more cavities in the glass substrate. Themethod can comprise removing the mask from the glass substratesubsequent to the exposing. The one or more cavities can have a patternthat corresponds to a pattern of the open region of the mask. Theetchant can comprise HF with a concentration of at most 2% by weight.The applying the mask can comprise applying the mask using a printingprocess. The mask can comprise an acrylic ester, a multifunctionalacrylate n-vinylcaprolactam, or a combination thereof.

Terminology and Interpretative Norms

The term “coupled” means the joining of two members directly orindirectly to one another. Such joining may be stationary in nature ormovable in nature. Such joining may be achieved with the two members orthe two members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate member being attachedto one another. Such joining may be permanent in nature or alternativelymay be removable or releasable in nature.

The terms “glass” and “glass composition” encompass both glass materialsand glass-ceramic materials, as both classes of materials are commonlyunderstood. Likewise, the term “glass structure” encompasses structurescomprising glass. The term “reconstituted wafer- and/or panel-levelpackage” encompasses any size of reconstituted substrate packageincluding wafer level packages and panel level packages.

The term “photosensitive glass composition” refers to a class of glassthat undergoes a change in crystallinity properties when exposed toradiation such as UV radiation. The term “photosensitivity” refers tothe degree to which a glass composition is susceptible to changes in itscrystallinity properties when exposed to radiation. Not all glasscompositions are photosensitive and, as such, glass that does notexhibit any photosensitivity has a photosensitivity of zero. Likewise,glass compositions that do exhibit some degree of photosensitivity havea nonzero photosensitivity.

The relative photosensitivities of two photosensitive glass compositionscan be determined objectively. For example, sheets of each compositionwith equal thicknesses may be exposed to radiation such as UV radiationfor various periods of time, followed by heat treatment, to determinethe minimum radiation exposure times that enable the secondarycrystalline phase to form through the entire thickness of each sheetafter the heat treatment. As applicable to embodiments described herein,a first photosensitive glass composition having a shorter minimumradiation exposure time than a second photosensitive glass compositionshall be considered to have a photosensitivity greater than that of thesecond photosensitive glass composition. Conversely, a firstphotosensitive glass composition having a longer minimum radiationexposure time than a second photosensitive glass composition shall beconsidered to have a photosensitivity less than that of the secondphotosensitive glass composition.

The term “photomachinable glass composition” refers to a photosensitiveglass composition that forms a secondary crystalline phase afterexposure of the photosensitive glass composition to radiation (such as,for example, UV radiation) and, optionally, a heat treatment. Thesecondary crystalline phase that forms after radiation exposure andoptional heat treatment is capable of being selectively removed by aphysical or chemical procedure such as selective etching.

The term “surface roughness” means Ra surface roughness determined asdescribed in ISO 25178, Geometric Product Specifications (GPS)—Surfacetexture: areal, filtered at 25 μm unless otherwise indicated. Thesurface roughness values reported herein were obtained using a Keyenceconfocal microscope.

The term “formed from” can mean one or more of comprises, consistsessentially of, or consists of. For example, a component that is formedfrom a particular material can comprise the particular material, consistessentially of the particular material, or consist of the particularmaterial.

Spatial or directional terms, such as “left,” “right,” “front,” “back,”and the like, relate to the subject matter as it is shown in thedrawings. However, it is to be understood that the described subjectmatter may assume various alternative orientations and, accordingly,such terms are not to be considered as limiting.

Articles such as “the,” “a,” and “an” can connote the singular orplural. Also, the word “or” when used without a preceding “either” (orother similar language indicating that “or” is unequivocally meant to beexclusive—e.g., only one of x or y, etc.) shall be interpreted to beinclusive (e.g., “x or y” means one or both x or y).

The term “and/or” shall also be interpreted to be inclusive (e.g., “xand/or y” means one or both x or y). In situations where “and/or” or“or” are used as a conjunction for a group of three or more items, thegroup should be interpreted to include one item alone, all the itemstogether, or any combination or number of the items. Moreover, termsused in the specification and claims such as have, having, include, andincluding should be construed to be synonymous with the terms compriseand comprising.

Unless otherwise indicated, all numbers or expressions, such as thoseexpressing dimensions, physical characteristics, and the like, used inthe specification (other than the claims) are understood to be modifiedin all instances by the term “approximately.” At the very least, and notas an attempt to limit the application of the doctrine of equivalents tothe claims, each numerical parameter recited in the specification orclaims which is modified by the term “approximately” should be construedin light of the number of recited significant digits and by applyingordinary rounding techniques.

All disclosed ranges are to be understood to encompass and providesupport for claims that recite any and all subranges or any and allindividual values subsumed by each range. For example, a stated range of1 to 10 should be considered to include and provide support for claimsthat recite any and all subranges or individual values that are betweenand/or inclusive of the minimum value of 1 and the maximum value of 10;that is, all subranges beginning with a minimum value of 1 or more andending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to3.56, and so forth) or any values from 1 to 10 (e.g., 3, 5.8, 9.9994,and so forth).

All disclosed numerical values are to be understood as being variablefrom 0-100% in either direction and thus provide support for claims thatrecite such values or any and all ranges or subranges that can be formedby such values. For example, a stated numerical value of 8 should beunderstood to vary from 0 to 16 (100% in either direction) and providesupport for claims that recite the range itself (e.g., 0 to 16), anysubrange within the range (e.g., 2 to 12.5) or any individual valuewithin that range (e.g., 15.2).

The drawings shall be interpreted as illustrating one or moreembodiments that are drawn to scale and/or one or more embodiments thatare not drawn to scale. This means the drawings can be interpreted, forexample, as showing: (a) everything drawn to scale, (b) nothing drawn toscale, or (c) one or more features drawn to scale and one or morefeatures not drawn to scale. Accordingly, the drawings can serve toprovide support to recite the sizes, proportions, and/or otherdimensions of any of the illustrated features either alone or relativeto each other. Furthermore, all such sizes, proportions, and/or otherdimensions are to be understood as being variable from 0-100% in eitherdirection and thus provide support for claims that recite such values orany and all ranges or subranges that can be formed by such values.

The terms recited in the claims should be given their ordinary andcustomary meaning as determined by reference to relevant entries inwidely used general dictionaries and/or relevant technical dictionaries,commonly understood meanings by those in the art, etc., with theunderstanding that the broadest meaning imparted by any one orcombination of these sources should be given to the claim terms (e.g.,two or more relevant dictionary entries should be combined to providethe broadest meaning of the combination of entries, etc.) subject onlyto the following exceptions: (a) if a term is used in a manner that ismore expansive than its ordinary and customary meaning, the term shouldbe given its ordinary and customary meaning plus the additionalexpansive meaning, or (b) if a term has been explicitly defined to havea different meaning by reciting the term followed by the phrase “as usedin this document shall mean” or similar language (e.g., “this termmeans,” “this term is defined as,” “for the purposes of this disclosurethis term shall mean,” etc.). References to specific examples, use of“i.e.,” use of the word “invention,” etc., are not meant to invokeexception (b) or otherwise restrict the scope of the recited claimterms. Other than situations where exception (b) applies, nothingcontained in this document should be considered a disclaimer ordisavowal of claim scope.

The subject matter recited in the claims is not coextensive with andshould not be interpreted to be coextensive with any embodiment,feature, or combination of features described or illustrated in thisdocument. This is true even if only a single embodiment of the featureor combination of features is illustrated and described in thisdocument.

INCORPORATION BY REFERENCE

The entire contents of each of the documents listed below areincorporated by reference into this document. If the same term is usedin both this document and one or more of the incorporated documents,then it should be interpreted to have the broadest meaning imparted byany one or combination of these sources unless the term has beenexplicitly defined to have a different meaning in this document. Ifthere is an inconsistency between any of the following documents andthis document, then this document shall govern. The incorporated subjectmatter should not be used to limit or narrow the scope of the explicitlyrecited or depicted subject matter.

-   -   U.S. Pat. No. 9,340,451 (application. Ser. No. 13/798,479),        titled “Machining of Fusion-Drawn Glass Laminate Structures        Containing a Photomachinable Layer,” filed on 13 Mar. 2013,        issued on 17 May 2016 (the '451 patent).    -   U.S. Pat. App. Pub. No. 2017/0073266 (application Ser. No.        15/125,453), titled “Glass Article and Method for Forming the        Same,” filed on 12 Mar. 2015, published on 16 Mar. 2017 (the        '266 application).

EXAMPLES

Various embodiments will be further clarified by the following examples.

A plurality of core glass compositions, which can be suitable for use asa core glass layer of a structured article, were prepared according tothe batch compositions listed in Table 1 below. Batches of the oxideconstituent components were mixed, melted, and formed into glass plates.The properties of the glass melt and the resultant structured articlewere measured and the results are reported in Table 2. The etch ratesreported in Table 2 are expressed in terms of weight loss relative tothe original weight of the sample after contact by a 50 vol % aqueousHCl solution at 60° C. in an ultrasonic bath for 30 min.

TABLE 1 Exemplary Core Glass Compositions SiO2 Al₂O₃ B₂O₃ Na₂O K₂O MgOCaO SnO₂  Sample   (mol %)   (mol %)   (mol %)   (mol %)   (mol %)  (mol %)   (mol %)   (mol %)  1-1 66   10.26 0.58 14.23 2.37 5.75 0.590.21 1-2 69.18  8.47 0   13.92 1.16 6.54 0.53 0.19 1-3 68.84 10.63 0  14.86 0.02 5.43 0.04 0.17 1-4 67.45 12.69 3.67 13.67 0.02 2.36 0.03 0.09

TABLE 2 Properties of Exemplary Core Glass Compositions LiquidusLiquidus Etch Rate CTE Temp Visc Strain Pt Anneal Pt Soft Pt DensitySample (%) (× 10⁷/° C.) (° C.) (kP) (° C.) (° C.) (° C.) (g/cm³) 1-10.01 91.1 900 4250 551 600 843 2.452 1-2 0.01 83.6 950 1498 560 609 8442.444 1-3 0   80.1 1070  nm 602 652 900 2.432 1-4 0   74.6 1002  2210589 644 922 2.403

A plurality of clad glass compositions, which can be suitable for use asa glass cladding layer of a structured article, were prepared accordingto the batch compositions listed in Table 3 below. Batches of the oxideconstituent components were mixed, melted, and formed into glass plates.The properties of the glass melt and the resultant structured articlewere measured and the results are reported in Table 4. The etch ratesreported in Table 4 are expressed in terms of weight loss relative tothe original weight of the sample after contact by a 50 vol % aqueousHCl solution at 60° C. in an ultrasonic bath for 30 min.

TABLE 3 Exemplary Clad Glass Compositions SiO₂ Al₂O₃ B₂O₃ CaO Li₂O Na₂OK₂O SnO₂ ZrO₂ P₂O₅ Sample (mol %) (mol %) (mol %) (mol %) (mol %) (mol%) (mol %) (mol %) (mol %) (mol %) 2-1 57 18.8 5 0 0 18.7 0.5 0.1 0.02 02-2 55 18.8 7 0 0 18.7 0.5 0.1 0.02 0 2-3 53 18.8 9 0 0 18.7 0.5 0.10.02 0 2-4 51 18.8 11 0 0 18.7 0.5 0.1 0.02 0 2-5 49 18.8 13 0 0 18.70.5 0.1 0.02 0 2-6 57 18.8 5 0 2 16.7 0.5 0.1 0.02 0 2-7 57 18.8 5 0 414.7 0.5 0.1 0.02 0 2-8 57 18.8 5 0 8 10.7 0.5 0.1 0.02 0 2-9 57 18 7 00 18 0 0.1 0 0  2-10 57 17 9 0 0 17 0 0.1 0 0  2-11 57 16 11 0 0 16 00.1 0 0  2-12 57 15 13 0 0 15 0 0.1 0 0  2-13 57.13 13.96 15.16 0.02 013.63 0 0.09 0 0  2-14 57 13 17 0 0 13 0 0.1 0 0  2-15 57.9 15 10 2 0 150 0.1 0 0  2-16 57.9 15 10 2 0 12 3 0.1 0 0  2-17 57.9 15 10 2 0 9 6 0.10 0  2-18 57.9 15 10 2 0 6 9 0.1 0 0  2-19 57.9 15 10 2 0 3 12 0.1 0 0 2-20 55 15 13 2 0 6 9 0.1 0 0  2-21 55 15 13 2 0 9 6 0.1 0 0  2-22 5515 13 2 0 12 3 0.1 0 0  2-23 55 15 13 2 0 15 0 0.1 0 0  2-24 53 15 15 20 6 9 0.1 0 0  2-25 53 15 15 2 0 9 6 0.1 0 0  2-26 53 15 15 2 0 12 3 0.10 0  2-27 53 15 15 2 0 15 0 0.1 0 0  2-28 51 15 17 2 0 6 9 0.1 0 0  2-2951 15 17 2 0 9 6 0.1 0 0  2-30 51 15 17 2 0 12 3 0.1 0 0  2-31 51 15 172 0 15 0 0.1 0 0  2-32 56 16 11 2 0 16 0 0.07 0 0  2-33 56 16 11 4 0 160 0.07 0 0  2-34 56 18 7 1 0 18 0 0.07 0 0  2-35 56 18 7 2 0 18 0 0.07 00  2-36 56 18 7 4 0 18 0 0.07 0 0  2-37 55 17 11 0 0 17 0 0.07 0 0  2-3854 17.5 11 0 0 17.5 0 0.07 0 0  2-39 53 18 11 0 0 18 0 0.07 0 0  2-40 5516 13 0 0 16 0 0.07 0 0  2-41 54 16 14 0 0 16 0 0.07 0 0  2-42 53 16 150 0 16 0 0.07 0 0  2-43 57 17.5 7 0 0 18.5 0 0.1 0 0  2-44 57 17 7 0 019 0 0.1 0 0  2-45 57 16.5 7 0 0 19.5 0 0.1 0 0  2-46 57 16 7 0 0 20 00.1 0 0  2-47 57 15.5 7 0 0 20.5 0 0.1 0 0  2-48 57 15 7 0 0 21 0 0.1 00  2-49 49 15 19 2 0 15 0 0.1 0 0  2-50 47 15 21 2 0 15 0 0.1 0 0  2-5145 15 23 2 0 15 0 0.1 0 0  2-52 57 16 11 10 0 16 0 0.1 0 0  2-53 57 14.514 0 0 14.5 0 0 0 0  2-54 57 15 13 2 0 15 0 0 0 0  2-55 57 14.5 14 2 014.5 0 0 0 0  2-56 57 14 15 2 0 14 0 0 0 0  2-57 57 17.5 7 1 0 18.5 00.1 0 0  2-58 57 17.5 7 2 0 18.5 0 0.1 0 0  2-59 57 17.5 7 0 0 19.5 00.1 0 0  2-60 57 17.5 7 0 0 18.5 0 0.1 0 3  2-61 57 17.5 7 0 0 18.5 00.1 0 6  2-62 53 14.5 17 1 0 14.5 0 0.1 0 0  2-63 51 14.75 18 1.5 014.75 0 0.1 0 0  2-64 57 18.8 5 0 0 18.7 0.5 0.1 0.02 0  2-65 57 18 7 100 18 0 0.1 0 0  2-66 57 17 9 10 0 17 0 0.1 0 0  2-67 57 17.5 7 4 0 18.50 0.1 0 0  2-68 60 15.38 0 0 0 16.49 0 0.1 0 5.15

TABLE 4 Properties of Exemplary Clad Glass Compositions LiquidusLiquidus Etch Rate CTE Temp Visc Strain Pt Anneal Pt Soft Pt DensitySample (%) (× 10⁷/° C.) (° C.) (kP) (° C.) (° C.) (° C.) (g/cm³) 2-122.85 92.7 1085 573 612 668 925 2.428 2-2 16.89 92.6 1035 584 581 633881 2.410 2-3 12.55 92.6 985 824 557 608 847 2.420 2-4 23.73 92.4 950898 539 588 813 2.401 2-5 28.92 92.8 900 >2000 522 570 789 2.388 2-61.96 92.5 1030 776 580 634 883 2.428 2-7 0.94 89.8 970 1326 557 607 8492.427 2-8 13.67 84.7 1000 233 541 590 814 2.410 2-9 9.28 85.0 910 >2000569 624 864 2.407  2-10 6.76 88.0 790 >2000 594 648 899 2.385  2-11 6.2979.1 775 >2000 524 576 821 2.369  2-12 3.33 82.3 770 >2000 544 596 8422.350  2-13 2.13 73.0 742 >2000 493 541 779 2.330  2-14 2.53 74.9760 >2000 508 557 790 2.310  2-15 1.55 76.4 950 1106 543 591 819 2.394 2-16 1.94 82.1 770 >2000 535 583 814 2.394  2-17 2.99 85.1 750 >2000526 577 819 2.392  2-18 5.25 87.0 940 >2000 528 578 836 2.388  2-1910.31 87.7 1155 68 536 589 849 2.384  2-20 5.09 87.5 770 >2000 516 565809 2.370  2-21 7.15 85.8 795 >2000 513 561 789 2.377  2-22 4.59 84.6760 >2000 514 559 772 2.382  2-23 5.31 79.5 750 >2000 526 571 776 2.385 2-24 9.19 87.1 750 >2000 503 552 777 2.357  2-25 5.73 86.3 775 >2000498 544 760 2.366  2-26 3.97 84.1 770 >2000 502 547 749 2.374  2-27 6.0979.2 795 >2000 511 554 744 2.377  2-28 9.89 85.4 715 >2000 491 538 7602.348  2-29 10.74 86.5 735 >2000 487 533 735 2.355  2-30 14.37 84.9750 >2000 491 534 731 2.364  2-31 9.73 79.4 790 >2000 501 544 726 2.368 2-32 5.28 81.3 765 >2000 521 566 769 2.405  2-33 6.34 80.9 910 294 524566 753 2.435  2-34 12.74 88.4 1000 524 555 604 837 2.425  2-35 15.1287.8 1000 281 545 591 813 2.439  2-36 14 87.4 1030 59 544 589 797 2.465 2-37 15.76 87.1 760 >2000 523 570 800 2.385  2-38 17.13 88.2 750 >2000521 571 800 2.388  2-39 17.13 90.2 840 >2000 521 570 794 2.394  2-407.86 83.6 800 >2000 503 551 785 2.365  2-41 7.84 83.1 770 >2000 495 544770 2.361  2-42 12.58 82.8 800 >2000 492 540 762 2.356  2-43 12.28 90.81000 773 553 601 841 2.428  2-44 12.89 91.4 990 366 545 592 821 2.432 2-45 22.9 92.7 970 292 534 577 771 2.442  2-46 22.1 92.1 970 149 528572 766 2.450  2-47 24.44 94.5 960 90 524 564 743 2.459  2-48 28.93 94.5950 89 519 559 735 2.461  2-49 22.85 80.0 765 >2000 493 533 712 2.367 2-50 16.21 79.3 750 >2000 484 525 702 2.355  2-51 16.89 80.0 775 1171476 517 688 2.346  2-52 8.56 82.7 935 66 534 574 736 2.495  2-53 2.4479.3 735 >2000 508 556 798 2.343  2-54 2.68 78.5 795 >2000 519 561 7642.391  2-55 2.9 77.1 840 >2000 515 557 744 2.382  2-56 2.14 75.9765 >2000 510 553 741 2.375  2-57 15.1 90.3 1010 150 534 579 798 2.442 2-58 9.66 89.6 1020 85 530 573 784 2.452  2-59 16.69 93.1 1020 150 532576 791 2.439  2-60 3.02 89 800 >2000 530 581 823 2.404  2-61 0.51 87.8810 >2000 514 564 800 2.395  2-62 2.84 76.7 740 >2000 502 546 763 2.348 2-63 4.19 78 775 >2000 500 542 737 2.355  2-64 15.63 94.5 970 414 609664 928 2.427  2-65 14.96 87.5 1070 10 544 584 762 2.513  2-66 13.2983.6 990 28 534 573 739 2.508  2-67 13.1 88.9 1020 42 531 574 764 2.473 2-68 0.05 84.4 990 >2000 630 704 957 2.422

As shown in Tables 2 and 4, the exemplary clad glass compositions areless durable (i.e., have higher etch rates) than the exemplary coreglass compositions in the selected etchant (i.e., 50% HCl).

A structured article is formed as described herein and comprises a glasscore layer formed from an exemplary core glass composition (e.g., Sample1-1 to 1-4) and a glass cladding layer formed from an exemplary cladglass composition (e.g., Sample 2-1 to 2-68).

Example 1

A glass composition available as Gorilla® Glass (Core 1) and a glasscomposition available as Lotus™ NXT Glass (Core 2) from CorningIncorporated (Corning, N.Y.) were selected as exemplary core glass. Theglass composition of Sample 2-13 (Clad) was selected as an exemplaryclad glass. The etch rate ratio or etching contrast between the coreglass and the clad glass depends on the glass compositions of the coreglass and the clad glass as well as the etching conditions. A variety ofetch rate ratios were achieved by varying the etching conditions (e.g.,etchant and etching temperature) as shown in Table 5. When the glasseswere etched in 2 wt % HF at 40° C., etch contrasts of 9 and 79 wereobtained for Clad/Core 1 and Clad/Core 2, respectively.

TABLE 5 Etching Contrast Between Core and Clad for Different EtchingConditions  Clad/Core 1   Clad/Core 2  Clad Core 1 Core 2 Etch Rate EtchRate Etchant  Temperature   Etch Rate   Etch Rate   Etch Rate  RatioRatio  (wt % HF)  (° C.) (μm/min) (μm/min) (μm/min) (μm/min) (μm/min)0.2 22 1.174 — — — — 0.5 22 2.27 — — — — 1 22 3.52 0.338 0.076 10.4146.32 2 22 5.58 0.694 0.152 8.04 36.71 0.2 30 2.15 0.07 — 30.7 — 0.5 304.46 0.244 — 18.3 — 1 30 6.22 0.472 0.134 13.2 46.42 2 30 10.44 1.240.304 8.42 34.34 0.2 40 7.76 0.126 — 61.6 — 0.5 40 7.95 0.25 0.094 31.884.6 1 40 8.896 0.78 0.156 11.4 57.02 2 40 16.64 1.85 0.212 8.99 78.5

FIG. 17 is a plot showing the etch rate of the clad glass on the x-axisand the ratio of the etch rate of the clad glass to the etch rate of thecore glass on the y-axis. The plot shown in FIG. 17 was developed byusing the same glass compositions (Clad and Core 1) and adjusting theetching chemistry to achieve a range of etching contrast from 5 to 30.FIG. 17 illustrates that the less aggressive etching condition (e.g.,corresponding to a lower clad etch rate) favors a higher etchingcontrast.

Example 2

Glass substrates having the general configuration shown in FIG. 1 wereformed. The glass core layers were formed from the glass compositionavailable as Gorilla® Glass (Core 1), and the glass cladding layers wereformed from the glass composition of Sample 2-13 (Clad). To demonstratethe etch stop function provided by the glass core layer at the core/cladinterface, glass substrates with different clad thicknesses were exposedto 1 wt % HF for various times, and the removal depth was measured. FIG.18 is a plot showing the etch time on the x-axis and the removal depthon the y-axis for the glass substrates with clad thicknesses of about100 μm (thin clad). FIG. 19 is a plot showing the etch time on thex-axis and the removal depth on the y-axis for the glass substrates withclad thicknesses of about 200 μm (thick clad). FIGS. 18-19 illustratethat the depth of the cavities stops growing with increasing etch timeat 100 μm, which is the thickness of the clad, for the glass with thethin clad, while the depth of the cavities continues growing withincreasing etch time for the glass with thick clad. Thus, a combinationof a mild etching chemistry and a glass substrate with core and claddinglayers as described herein can provide a hard stop for the etching atthe core/clad interface, which can enable more precise and uniformcavities and other glass structures.

Example 3

Glass substrates having the general configuration shown in FIG. 1 wereformed. The glass core layers were formed from the glass compositionavailable as Gorilla® Glass (Core 1), and the glass cladding layers wereformed from the glass composition of Sample 2-13 (Clad). The glasscladding layers had a thickness of about 100 μm.

High precision of the cavities can be indicated by relatively littlevariance in a z-depth difference (e.g., the difference between the firstdepth of the cavity at the first position along the perimeter of thecavity and the second depth of the cavity at the second position alongthe perimeter of the cavity opposite the first position), a widthdifference (e.g., a difference between a first width at the top of thecavity near the surface of the shaped article and a second width at thebottom of the cavity near the floor of the cavity), and a roughness ofthe cavity (e.g., the sidewalls and/or the floor) within in one piece(e.g., one shaped article) and among pieces. To evaluate the precisionof the cavities using the wet etching process described herein, 2 wt %HF was used to etch the masked glass substrates at etching temperaturesof 22° C. and 35° C. for different etch times. The results aresummarized in Table 6. FIG. 20 is a cross-sectional schematic view of acavity formed in the glass substrate, showing the dimensions referencedin Table 6.

TABLE 6 Dimensions of Cavities Formed by Wet Etching ΔW Etch ΔZ (mm)Temperature Etch time Z_(left) Z_(right) (μm) W_(top) W_(bottom)(W_(top)- Ra Etchant (° C.) (min) (μm) (μm) (Z_(left)-Z_(right)) (mm)(mm) W_(bottom)) (nm) 2 wt % HF 22 50 97 97 0.1 10.4 9.7 0.7 1.8 60 100100 0.0 10.4 9.7 0.7 3.0 70 100 100 0.2 10.4 9.7 0.7 6.8 35 20 95 93 2.010.2 9.6 0.6 1.0 25 98 98 0.4 10.3 9.6 0.7 1.4 30 107 105 2.0 10.3 9.60.7 2.4

As a result of the hard etch stop provided by the glass core layer atthe core/clad interface, increasing the etch time did not substantiallyincrease the removal depth (e.g., the cavity depth). On average, thez-depth or cavity depth was measured to be 99.5 μm for all conditions,which was close to the expected value of 100 μm. The mask was found toremain adhered to the glass during the etching process, which enabledthe width of the cavities to be 10.3 mm, close to the expected value of10 mm. In addition, the z-depth difference across a cavity was less than2 μm, and the width difference between the width at the top of thecavity and the width at the bottom of the cavity was 0.7 μm. Thecavities also were found to be smooth and flat. The average surfaceroughness was less than 7 nm. It is believed that such low roughness mayhave been enhanced by a horizontal etching and stirring solution, whichcan help to remove the etching byproduct from glass surface quickly sothat it will not mask and roughen the glass surface during the etching.

Wall angle can be an important attribute for the cavities or wells usedfor electronics manufacturing (e.g., IC packaging). FIG. 21 is aphotograph of a cavity formed using a conventional wet etching processon a single-layer substrate. As shown in FIG. 21 , the conventionalprocess results in a bowl-shaped cavity with tilted sidewalls and roundcorners. In contrast, FIG. 22 is a series of photographs of cavitiesformed using the process described herein. As shown in FIG. 22 , theetch stop provided by the glass core layer at the core/clad interfaceenables extended etching time without substantially affecting the depthof the resulting cavity. Thus, the etching during the extended etchingtime mainly occurs at the corner areas near the intersection between thesidewalls and the floor of the cavity, which can enable improved wallangle (e.g., reduced wall angle and/or straighter sidewalls). As shownin FIG. 22 , when etching the glass substrate in 2 wt % HF at 35° C.,extending the etch time from 20 minutes to 30 minutes reduced the wallangle from 43° to 18° and substantially removed the round corner.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the claimed subject matter. Accordingly, the claimedsubject matter is not to be restricted except in light of the attachedclaims and their equivalents.

The invention claimed is:
 1. A structured glass article, comprising: aglass substrate comprising a glass cladding layer fused to a glass baselayer; and one or more cavities formed in the glass cladding layer, eachcavity extending from a surface of the glass cladding layer and having adepth, wherein the glass base layer defines a floor of each cavity andthe glass cladding layer defines one or more sidewalls of each cavity,and wherein a distance across each cavity between opposed portions ofthe one or more sidewalls, when measured at a first depth proximate thesurface and at a second depth proximate the floor, differs by at most 1mm in a direction normal to the depth.
 2. The structured glass articleof claim 1, wherein the glass cladding layer has a higher etch rate inan etchant than the glass core layer.
 3. The structured glass article ofclaim 1, wherein a first photosensitivity of the glass cladding layer isgreater than a second photosensitivity of the glass base layer.
 4. Thestructured glass article of claim 1, wherein the distance across eachcavity passes through a centroid of the cavity at the first and seconddepths.
 5. The structured glass article of claim 1, wherein the floor ofthe one or more cavities comprises a surface roughness of at most about20 nm.
 6. The structured glass article of claim 1, wherein the depth ofeach cavity comprises a third depth at a first position along aperimeter of the cavity and a fourth depth at a second position alongthe perimeter of the cavity opposite the first position, the third depthand the fourth depth differing by at most about 5μm.
 7. The structuredglass article of claim 1, wherein the depth of each cavity correspondsto a thickness of the glass cladding layer.
 8. The structured glassarticle of claim 1, wherein an angle formed between the one or moresidewalls and the floor of each cavity is at most about 30°.
 9. Thestructured glass article of claim 1, wherein the distance across eachcavity corresponds to a width of each cavity and a difference between afirst width at a top of the cavity and a second width at a bottom of thecavity is at most about 1 mm in a direction normal to the depth.
 10. Thestructured glass article of claim 9, wherein the depth of each cavity isat least about 50 μm.
 11. A packaged integrated circuit, comprising: astructured glass article comprising a glass cladding layer fused to aglass base layer and a cavity formed in the glass cladding layer, thecavity extending from a surface of the glass cladding layer and having adepth, the glass base layer defining a floor of the cavity and the glasscladding layer defining one or more sidewalls of the cavity; and anintegrated circuit chip disposed within the cavity, the integratedcircuit chip having a peripheral surface that faces the one or moresidewalls of the cavity, wherein a gap between the peripheral surfaceand the one or more sidewalls is no more than 20 μm in a directionnormal to the depth.
 12. The packaged integrated circuit of claim 11,wherein the depth of the cavity is no more than 20 μm larger than athickness of the integrated circuit chip.
 13. The packaged integratedcircuit of claim 11, wherein the depth of the cavity is about 5% toabout 90% of a thickness of the integrated circuit chip.
 14. Thepackaged integrated circuit of claim 13, comprising a planarizing layerdisposed on the structured glass article adjacent the integrated circuitchip.
 15. The packaged integrated circuit of claim 11, wherein thepackaged integrated circuit is free of resin molding compound disposedwithin the cavity.
 16. The packaged integrated circuit of claim 11,wherein a difference between a first depth of the cavity at a firstposition along a perimeter of the cavity and a second depth of thecavity at a second position along the perimeter of the cavity oppositethe first position is at most about 5 μm.
 17. The packaged integratedcircuit of claim 11, comprising a redistribution layer disposed on theintegrated circuit chip.
 18. The packaged integrated circuit of claim17, comprising a ball grid array disposed on the redistribution layer.19. The packaged integrated circuit of claim 11, wherein: the glasscladding layer comprises a first glass cladding layer fused to a firstside of the glass base layer and a second glass cladding layer fused toa second side of the glass base layer opposite the first glass claddinglayer; the cavity comprises a first cavity formed in the first glasscladding layer and a second cavity formed in the second glass claddinglayer; and the integrated circuit chip comprises a first integratedcircuit chip disposed within the first cavity and a second integratedcircuit chip disposed within the second cavity.
 20. The packagedintegrated circuit of claim 19, wherein the glass base layer isnon-transmissive to radiation useful to expose at least one of the firstglass cladding layer or the second glass cladding layer to form thecavity therein.
 21. A wafer- or panel-level package comprising thepackaged integrated circuit of claim 11, wherein: the cavity comprises aplurality of cavities, and the integrated circuit chip comprises aplurality of integrated circuit chips each disposed within one of theplurality of cavities.
 22. A method for making a reconstituted wafer-and/or panel-level package, the method comprising: forming a pluralityof cavities in a glass substrate comprising a glass cladding layer fusedto a glass base layer, each cavity extending into the glass claddinglayer from a surface thereof and having a depth; and positioning anintegrated circuit chip in each of the plurality of cavities in theglass substrate, the integrated circuit chip having a peripheral surfacethat faces one or more sidewalls of the cavity, wherein a gap betweenthe peripheral surface and the one or more sidewalls is no more than 20μm in a direction normal to the depth.